This invention is in the area of medical devices, in particular in the area of medical devices for drug delivery, more in particular for controlled release of drugs to the eye.
Delivery of drugs to the anterior side of the eye is routinely done with eye drops, but this method results in low bioavailability and low patient compliance. Devices that address these problems have been described for the delivery of drugs to the eye. One of such devices, called the OphthaCoil, consists of a thin metallic wire, which is coiled and carries a drug-loaded adherent hydrogel coating on its surface. The drug is then released in a more or less controlled fashion in vitro as well as in vivo (Pijls et al., Eur. J. Pharm. Biopharm. 59, 283 (2005)).
By using this device, anti-microbial drug levels in the tear fluid of dogs could well be maintained above the MIC-values of relevant bacteria after 16 hours, using pradofloxacin, a very potent anti-microbial drug. The devices were well tolerated, but may be lost when left in the eye overnight.
The drug loading capacity of the OphthaCoil, however, becomes the limiting factor when less potent drugs are to be delivered to the eye. Several strategies have been suggested to solve this problem. First, it was suggested to fill the coil with a hydrogel. When polymerizing a hydrogel in the lumen itself, it appeared that the coil lost its flexibility. The loss of flexibility is detrimental for the patient, since the device is no longer tolerated when rigid. The solution was found in that a number of straight wires, made of the same material as the wires constituting the coil, was inserted into the coil. The straight wires were coated with the same coating as the coil and so increased the drug load of the assembled device. The coils thereby lost some of their flexibility by that process.
Therefore, it remains desirable to increase the drug loading capacity of such coiled devices while maintaining or improving the flexibility.